Thanks everyone for the instructions on how to do this. I just attempted this weekend since the dash was apart to replace the blower motor, and it seems to be working well! I used the separate L- and R- connections (pins 4 & 6 instead of 7) for the left & right channel grounds, and it sounds very clear regardless of whether the phone is charging or not. I also added a USB port connected to the cigarette lighter for charging, and a pocket where the blank panel/cassette player would otherwise live.

yes I was right "assuming" that the ground would be pin 14. Unfortunately i forgot to clean the lens physically so the only problem I had today morning was skipping cd during driving on not flat roads. Then I put a self-made lens cleaner and cleaned the laser. The disk never skips now, finds track much faster and keeps it. I want to try to write a blank CD with 2 tracks. The first 70 min silence and the second 5 or 10 minute silence tracks and put the last i.e. second track on repeat mode. In this case the second track would be written on the outer bigger radius part of the cd and I think it would be "easier" for the laser head to read data. I will give a try tomorrow and post my results. Also I modified my old Griffin Road Trip FM modulator and took Ipod lineout from it and it is charging and playing the same time holding my ipod in vertical position switched in sigarete lighter. Also when i turn off the engine, Ipod stops automatically.

In any case, I want to thank you for a BRILLIANT idea. The difference is HUUUUUUUUUGE. I have JBL sub with pioneer amp installed and it delivers MUCH better power via AUX rather from FM modulator.

EDIT: CANCEL THAT it worked just fine
A bit late to the game; but I recently acquired a decent 2004 Mazda 6, I'm attempting buba and Dragan's method at page 8 but mine has a Bose setup(no small side PCB):Link to album with some more details
Top chassis:
Bottom PCB:

I just spent half the day trying to do this. Lessons learned.
1. Don't use a headphone cable. They have Teflon, Kevlar, or whatever those strands are that refuse to get out of the way. And then you have to melt the enamel off the wires which never seems to burn off all the way. Use an extension cable or a thicker cable that came with PC speakers. They usually have 3 rubber coated wires LEFT, RIGHT and Shield (Bare).
2. Don't go back and forth between the picture of the radio and the wiring diagram. One is upside down and it will confuse the snot out of you. Especially since one is labeled 1234 and the other is ABCD.
3. Not sure why but when I pluged it in upside down my radio allowed media mode but had no audio. Not sure why that worked the way it did.
4. I wired RIGHT to 3(2C) and LEFT to 5(2E) and split the audio shield between 4(2D) and 6(2F) and left 2G empty. This resulted in the LEFT and RIGHT being out of phase with each other which doesn't make any audio or electrical sense at all. I moved the pin from 6(2F) to 7(2G) and everything sounded fine.
5. The shortest most difficult connector to plug in is the radio cable. the other one is for AC I think.
6. I was delightfully surprised that the radio remembers different volume levels for each source.
7. To pull the pins out of the CD audio cables a safety pin works best. It's sharp strong and wont slice your finger open.
8. I soldered the headphone cable directly to the pin. I hate soldering two wires toghether it never holds well. I used an old IDE drive to hold the pins still while I soldered.
9. IDE cables don't fit. The pins are distanced just slightly too small to just lop off the first 16 pins of a floppy cable. (that was the first hour of my frustration)

Stuck CDs

Originally Posted by FrankCarrillo

OK, after some searching in the thread, I found a number of potential solutions which involve my soldering wires to the PCB board and playing a "silent CD" (Posted by Dragan and buba). Not sure I can follow those instructions completely - see my reference to my soldering skills... :-)

Has anyone figured out an alternate solution? Really frustrating that Mazda did not make the radio a little more flexible in being able to add a simple AUX input.

Do you think this will work with my CD changer saying "do disk" with cds stuck inside it?
Any ideas would be much appreciated

Thanks to the OP and all who have contributed. I've used this info today to convert my 2004 non-Bose Mazda 6 touring to have an aux input using buba's blank CD method with Dragan's trick of soldering direct to the PCB. Reminder - do not try to short pin 13 on the back of the radio on a pre-2006 car! I'll add some pics and notes from what I learned, in case it helps anyone:

Upper board after wires soldered:image.jpeg
Pinout is the same as the (labelled) connector on the lower board. The ribbon cable is direct pin to pin after all. So from left on the top row you have audio right, audio left. On the bottom row the LHS pin is audio ground. Do use hot glue to anchor the cables before you solder them!

Ok, lessons learned.

- First, the tip to refit the gear knob is a good one, it does save scratching your trim
- Second, the cup holders on the 2004 car don't have the plastic tabs referred to in the OP, you simply grab the whole unit including fascia and pull it up hard. Then squeeze the two tabs which lock it to the next panel (gearshift fascia) and release them
- it feels so wrong to start pulling your car apart but I suffered no snapped clips or damaged plastics. Trust the instructions and use a bit of grunt
- when removing the centre trim you need to unplug at the rear of the radio and the side of the radio, but the lower connectors can stay attached. You can unscrew and remove the radio without taking them apart.
- taking the top off the radio doesn't require removal of any screws, just prize it off with a flat blade screwdriver
- a magnetised small crosspoint Philips screwdriver will be very handy for removing the CD player, as the two screws at the front are buried deep
- remember to thread the audio cable / cables thru holes in the case BEFORE you hot glue and solder them
- I soldered to the top board (the one which is attached to underside of the CD player) and found this much easier than the lower board, as it's more accessible. Even though the lower board is the one which is labelled, the connections do of course make it through that ribbon cable in a straight line, so you can see easily enough where they appear on the top board.
- use hot glue to hold the cable close to the solder connections, and more to anchor the cable as it leaves the PCB. Use a cable tie to strain relieve the cables as they pass through the radio case. You don't want to be taking the radio apart and resoldering because someone dropped their phone and gave the audio cable a tug.

I think that's it. It was a lot easier than I expected. Only hard parts were getting started on taking out the cup holders, and persuading my old windows laptop to burn a blank audio cd!

I've recently bought myself a Mazda 6 estate 2003...it's a runner for work but it's still in a very tidy condition and at a steal for £600 with 12 months MOT and no advisories, drives sweet as a nut...very happy indeed.

I'd like to thank the guys here for discussing this mod as it's helped big time, i'm all about the comforts and having the aux jack in my car is one thing I have to have...

What brings me here is after installing this mod, this was done by soldering the headphone cable or in my case a 3.5mm jack to 3.5mm jack with one end cut off to the CD PCB inside the stereo. I've done that with the cable then coming out of the top center pocket (where the satnav would be if I had one) but also I've added another cigarette lighter socket which if tee'd of the original cigarette light and hid that behind the dash/radio with the USB charging cable also coming through the same hole in the center pocket, this then means I have a permanent phone/tablet charger without bottlenecking the 12v socket and no messy wires. I've done the thing with the hinge (YouTube - Galaxy Tab im Mazda 6 (sorry for advertising another website) for those who haven't seen this) with my Samsung Tab 3 and works/fit's/looks great, except one thing...I get a hum/frequency noise that get more high pitched with the engines revs but this only happens when it's charging if I disconnect the USB then it's goes away. I'm assuming this is some kind of ground issue...

Before I take my dash apart again to take a look which will probably be at weekend, I was wondering if anyone might have any idea's or even better a guarantee for the fix, again thanks this thread alone has been big help.